The 40V max XGT® 4.0Ah Battery is engineered to outlast the competition. XGT Batteries feature an advanced design with an impact-resistant outer case and shock-absorbing inner-liner that are engineered to protect the battery in harsh jobsite environments. XGT Batteries also feature rigid rails with impact-resistant construction to secure the battery to the tool during high-demand applications. 40V max XGT Batteries are equipped with smart technology. The digital communication within XGT Batteries optimizes performance to provide up to 2X longer sustained power under heavy-load applications. The digital communication within XGT Batteries and Chargers (sold separately) actively monitors and protects against overload, over-discharge and overheating. This advanced charging technology helps optimize battery life and deliver a faster charge. The battery reaches a full charge in only 45 minutes or less.